Communication and posting system



June 28, 1949.

E. L. SCHMIDT COMMUNICATION AND POSTING SYSTEM Filed Feb. 6, 1945 7 Sheets-Sheet 1 T H m N m M G T S .T L Q m 4 B v 0: mdE 2. 1 2.

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E. L. SCHMIDT COMMUNICATION AND POSTING SYSTEM June 28, 1949.

Filed Feb. 6, 1945 7 Sheets-Sheet 2 l TO FIG. 3

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EDWIN L. SCHMIDT ATTORN EY 7 Shee.ts -Sheet 3 June 28, 1949. E. SCHMIDT COMMUNICATION AND PO STING SYSTEM Filed Feb. 6, 1945 INVENTOR EDWIN L.sc| m|o'r ATTORNEY June 1949- I E. L. SCHMIDT 2,474,438

' COMMUNICATION AND POSTING SYSTEM Filed Feb. 6, 1945 '7 Sheets-Sheet 4 SECOND men IDENTIFICATION AGE AND ozcooms RELAYS 14-215 INVENTOR EDWIN L. SCHMIDT BY WW ATTORNEY June 28, 1949.

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Filed Feb. 6, 1945 DATA UNITS DECODING RELAYS nun-nus v :3 \oo v 4 a 3 v3 23 H N N I v FDN\ e3 Q M H m B :1 .8 um 63 E u gioh To INVENTOR EDWIN SCHMIDT ATTORNEY June 28, 1949. E, SCHMIDT 2,474,438

COMMUNICATION AND POSTING SYSTEM Filed Feb. 6, 1945 7 Sheets-Sheet 6 INVENTOR EDWIN I L. SGHMI DT BY m ATTORNEY June 28, 1949. E. 1.. SCHMIDT 2,474,433

' commumcnxon AND POSTING SYSTEM Filed Feb. 6, 1945 7 Sheets-Sheet 7 FLIGHT PROGRESS BOARD IFW'ITIWTTEWTIEWTJT FIX 3 PHILADELPHIA [5 IE] E m I] E! m w 9 @[2 |1 1 FIX 2 BALTIMORE I I] U I] E] 'l] U 1 [1|] [ID I] I] Y lEl-IEIEIU E 5 mm mm [1 m 5 4 Ell] Ell] III I] UUUUU El'ia Bl] El] [I I] 2 LEIIE [JU' Q L FlG.8

AYTTCRNEYI Patented June 28, 1949 UNITED STATES PATENT OFFICE COMMUNICATION AND POSTING SYSTEM Application February 6, 1945, Serial No. 576,398

19 Claims.

This invention relates generally to communication and posting systems for displaying information or data in regard to a number of different items by means of groups or rows of indicators which are automatically and selectively actuatable or settable in response to incoming signals to display information or current changes in information in regard to the items posted, and is particularly applicable, although not limited, to a system for the transmission, recordation and posting of data on announcement or bulletin boards relating to air trafllc control information, in which the signals representing the information thus posted may be transmitted either from a local transmitter or from wire or radio transmitters remotely situated with respect to the receiving, posting and recording apparatus, which remote transmitters may be located at ground stations or within aircraft in flight. The system disclosed herein represents in various respects an improvement over the communication and posting system-s disclosed in the Marshall et al. patent, No. 2,246,449, issued June 17, 1941, and in the May et al. Patent No. 2,386,743, issued October 9, 1945, and the Marshall et al. Patent No. 2,391,469, issued December 25, 1945, the disclosures of which, insofar as they are pertinent to the present invention, are incorporated herein by reference.

In systems for recording and posting flight plans and flight progress reports of aircraft and other messages relative to the control of aircraft, hereinafter referred to as air trafic control systerms, the information thus posted on the bulletin or announcing board usually relates to numerous flights, and the items posted usually are arranged in groups according to the various marker or Fix classifications, as explained in the aforesaid Marshall et al. patent, and preferably are arranged within each Fix group in accordance with the expected or estimated time of passage or arrival of the aircraft at the various recording or marker points en route and at the airport. The flight data posted may have to be changed from time to time during the progress of the flights as the result of conditions affecting the progress of aircraft, such as poor visibility, ice, changes in the direction and velocity of. the wind, the necessity for blind landings, and other emergency conditions.

The information posted may comprise numerous data, such as the flight designation symbols followed by a section number, if any; information as to the direction of the various flights; the airway traflic controllers estimated time when the aircraft will pass over or land at certain marker points on the flight route; the time the aircraft actually passes over or lands at each marker point; the expected approach time when the pilot may receive instructions to start his approach to a landing field; proposed altitudes at which a clearance has been issued to cross each marker or flight path; the altitude and time at which the aircraft actually crosses the various markers; and the landing sequence number assigned to landings under instrument conditions. In addition to the foregoing, other information may be posted on the flight progress display boards, such for example as an indication that a clearance through a fix or control zone has been issued; an indication of a flight over the airport; an indication of a stop en route, and the expected approach time, or that if a delay is encountered the degree of such delay is unknown; and an indication that an aircraft has been cleared to the airport control tower or range station so that there will be no unnecessary delay in landing.

Local communication facilities comprising known telephone or telegraph wire or radio equipment may be employed to establish communication between the air line company's dispatch offices and the various aircraft, airport control towers, the local communications operator of the airway traffic control, government regulating bureaus, local military operations offices, if any, and other airports.

In prior systems of the character disclosed herein, and particularly air traffic control systems, if an incoming message in regard to a particular flight or other item to be posted contained more than one kind of data for the same display item, for example, altitude and time, it was necessary to repeat the item or flight identification, including the fix, for each of the various kinds of data during the transmission of the message, and to effect the posting of the individual ranges of data relating to the item successively on the record or display board, thereby involving as many posting operations as there were different kinds, or ranges, of data. This causes an undesirable loss in time, both in the transmission and posting of the data, and also is subject to a further objection in that the several indicators for displaying an item posted on the display board are not simultaneously or concurrently reset when a change in data is to be effected, and thus for a period of time certain of the indicators assigned to an item may display current data while others are displaying obsolete data in regard to likelihood of confusion, and results in a faster and more efficient system since the posting time is greatly reduced. This saving in time is particularly important when a message is received.

as a result of an initial automatic retransmission from another center. In such cases, all available data pertaining to a specific flight or other item are embodied in a single message and, therefore, the postin of the display board at the receiving center usually comprises a plurality of data ra es- In air trafiic control procedure it is at times required that certain information displayed on a flight progress board at a traffic control center be retransmitted to another center or to an auxiliary board such, for example, as an airport control tower or ran e station. Such retransmissions are usually not made at the time the information is originally posted at the retransmitting point, but instead are initiated at some later period, depending upon the. progress of the flight in question. For example, assume that a flight plan is posted on a flight progress board at the Washington control center for. an aircraft. flying the New York to Washington airway. The Wash, ington airways traflic control center board would, in this instance, display the flight information at fix or check points in the Washington control area, viz.,-Philadelphia, Baltimore and Washington. play board is located: at. the Washington Airport tower. This latter board would. display information relative to. the Washington fix only, since the tower personnel are concerned only with traffic in the immediate vicinity of the Washington Airport.

It will be apparent that, while the airways trailic control board must display the Washington fix posting prior to theentrance of the flight 0 into, the Washington airways. control area (in the neighborhood of Philadelphia on a southbound flight), the Washington tower board does not require thisv information until a much later time when the aircraft is about to enter the immediate controlzone of the Washington tower. At this later. time, the tower board must duplicate the existing information displayed for the specific flight. on the Washington. flxsectionof the main airways traffic control board. The. retransmission to the tower board at this. time. is not necessarily a duplication of all the, previous messages which caused a displayof information on the Washington fix section ofthe main board, but rather re ra n is 9 t e l ntd s la I s ha ii atq n er ne a e r b a nn-r191 n ormat n, w zh ma have been revised by changing flightconditions ol o n the. Ori ina l; emi ion h w er n change the niqr g icri z sted aw a n board should automatic be relayed to, the Fe e e t s bab unde st tlihat etrans= m s q is 3. 11 imi d. 9311 93 93 3 1 b m de 9 cente mar n? antra rea. m ll: @13 0 7. va 9 1 191 lPF R :-Q 5 1 11.-

Assume further that an auxiliary dis- Another object of the invention is the provision of means operative upon the occurrence of a particular event or condition for automatically retransmitting selected data currently posted on a record or display board to another center or to an auxiliary board for recording or posting such information on the other board, thereby to dupimit. t ert in tim hel e i ed data. and th r after to cause changes efieoted in said data posted on the record or display board also to be effected automatically at the other center or auxiliary ea The information displayed on a given fix posting of a flight progress board is usually retained until the aircraft has reported over the next fix, or check point, on its course along the airway. Previous air traffic control systems have provided for a wipe-out of the obsolete display by means of a manuaLkeyset operation.

Another object of the present invention is to provide means for a wholly automatic wipe-out at the. previous fix posting, upon the occurrence of a particular event or condition, for. example, as whenan over. report isreceived i. e., the time at which anaircraft reaches. or passes a certain fix. Automatic reference may bev made to. the direction of flight, obtained from a.bound"' digit of the existing display, and the fix: section at which the. over reportisreceived; tosdetermine the previous fix section at which. the automatic wipe-out of the flight. posting. in. question must be. made. This wholly automatic featureelimip nates the manual. operationsheretofsore necessary and results in increased speed: and: efficiency.

An additional object of thev present invention is toprovidesuitable automatic alarm means to attract the immediate attention of: airwaysv traflic control personnel in theevent that certain special conditions occur or obtain, for example, as when an over? report is received from an unscheduled air-craft at any fix within the control area.

These and various other objects, advantages and improvements. of thepresent invention will beapparent from the following detailed description of one illustrative embodiment'of the invention taken in connection with the accompanying drawings, in which:

Fig. 1' is'aview indiagrammaticform of certain transmitting and receiving apparatus'including a seeker mechanism andmessage counting storage indicators suitable for use in the system of the invention;

Fig. 2'is a diagrammatic representation of the announcing or display board-containing storage displayindicators, together with the tens digit translating. relays and-certainidentification or flight locatorrelays;

Fig. 3. shows groups of:- translating relays with associated control, relaysand a retransmission distributor.- with associated control and; switching relays, the. figure also illustratingdiagrammati cally a retransmission. tape reperforator, tape transmitter l and. transmitting distributor;

Fig. 4.1 illustrates areceiving'distributor controlled by signals received-from the transmitting apparatus of Fig; 1;-, together with distributor control relays and the tens and; unit flight identi, fication ewdinerel y. oans...

Fig. 5-shows fix, range and data decodingre. a c iques. ra ge. tr nsfer, fix. and i e tion-J reays. and. lighti satilfica i nor e: ndicators n tag-sw ches.- emn cy dthe fli hti catqr, circuit;

la. h wsga-r lse.distrihutcr;.data storage and data'restoration groups and associated control relays;

Fig. 7 illustrates an arrangement of the display board on which the flight control information is posted;

ranges, such as estimated time, altitude and others previously mentioned herein, also would be transmitted, received and stored or posted generally in the manner of the ranges specifically referred to in the detailed description. Likewise, for simplicity, the number of denominational rows of digits for a particular range has been limited to one or two; in practice a greater number would be employed for certain ranges as well as for the flight identification groups.

Seeker and message counting circuits In the system of the aforesaid Marshall et al. Patent 2,246,449, a condition may arise wherein, assuming the operator at the remote sending point transmits another message over the same line before the end-of-message character in the first message has passed through the common retransmitting and posting system, the seeker connection is held by the auto-control contact of the associated tape transmitter, thus allowing the remote operator to post two or more independent messages in succession. In the present system the number of complete messages transmitted by a remote point preferably is counted by suitable means, such as a storage indicator unit, as the end-of-message character for each message is transmitted, and a second associated means, such as a storage indicator unit, is used to count the end-of-message character as it passes through the common retransmitting and posting equipment. Any disagreement in the settings of the associated indicator units is an indication to the seeker that an incoming message from the associated line is awaiting connection to the common posting system. With this feature, it is impossible for a partial message from a remote sending station to cause a tie-up of the common posting system, since no indication is given to the seeker at any time until a complete message, including the end-of-message character, has been received. Also, since a count of incoming messages up to ten in number is kept on the associated indicator unit, no lost postings will result due to a plurality of messages being received over a particular line at the time the common posting system is connected by the seeker to a different incoming line.

Assume, for example, that the flight progress board depicted in Fig. 7, is located at the Washington Airport, and messages are being trans- I mitted simultaneously from telegraph transmitters, for example, keyboard transmitting teleprinters land. 2, Fig. 1, over lines D and L2. Teleprinter I may, for example be located at the New York control center and is assumed to be in the process of transmitting two successive,

independent messages for posting on the Wash"- ington flight progress board, whereas teleprinter 2, which maybe located in an aircraft over the Baltimore flx is assumed to be in the process of transmitting an over report for display on the Washington board. A local transmitter 3, which may be a teleprinter, is provided to enable the personnel at the control center to post, reset or wipe-out the display at will.

The preliminary operations resulting from the transmission of the first message from the New York teleprinter will now be described. Assume the message concerns flight 35 and contains Bound and Control data for this flight at the Philadelphia fix section of the Washington board. The New Yor k operator actuates the keys of his teleprinter in the following order: 3532431L. The first two characters transmitted 35, represent the flight identification number; the third character 3, represents fix 3, or Philadelphia; the fourth character represents the range Bound; the fifth character 4, represents the direction data digit South; the sixth character 3, represents the range Control; the seventh character '1, represents the control data digit; and the eighth, or final, character L represents the endof-message signal. It should be explained here that the direction digits usually areassigned to correspond to points of the compass so that, starting with northeast as the digit 1 and progressing clockwise, the digit]; represent south direction and the digit 8 would represent north direction. For purposes of simplification, only the north and south direction circuits have been shown on the drawings. Likewise, the control data digit represents an arbitrary assignment to indicate the specific instruction issued to the pilot of the aircraft in question. For example, the digit 1, in the control range might indicate cleared to the New York boundary. This would be an indication to the Washington personnel that the New York control center had cleared flight 35 to the point where Washington assumes control. Other digits are assigned similarly, the digit 2, for example, could indicate instructed to hold at this fix, etc.

The keyboard printer referred to above may be one of any of the well known types suitable for the purpose such as, for example. what is known in the telegraph art as a 2B printer that records the signals on a tape in response to start-stop or simplex type signals, such signals being composed of marking and spacing line conditions comprising a start impulse followed by groups of permutations of five intelligence impulses in varous combinations representing the characters to -be transmitted or received, and each group being terminated by a rest impulse which is of opposite line condition to that of the start impulse. The actuation of any of the keys of theassociated keyboard causes the transmission of signals representing the character assigned to each key.

The operation of the flight indentification key causes a start signal to be applied to the line L, thereby starting operation of receiving distributor 4. Thissignal is followed by a five unit code permutation signal for the first digit (3) of the flight indentiflcation number, this signal having the code unit I thereof marking. and the code units 2, 3,4 and 5 spacing in character, Fig. 8, followed by a rest, or stop, signal. The operation of distributor 4 causes the marking and spacing code units I, 2, 3, 4 and 5 of the in: telligence 'signal to be transmitted to the tape reperforator 5'over the conductors 6, 1, 8, 9, and

M respectively; Following this, an--=impulse :is

transmitted .in 'known 2 manner by the distributor over conductor 4 l to operate the punch :magnet and-cause the reperforator rtolperforate the tape 1:2 issuing therefr-omin accordance with :the signals -:received and step the tape ahead into position :for the :nextssucceeding perforating .opera- 'tion corresponding to the second digit -.of the flight identification number. .Since the permutation signal for the digit 3:has .the code unit I only =marking in character, conductor i .is :energized and conductors =1, 8.4! and Mare deenergized,therebycausing asingle perforation correspondingto-the codeunit l to-be made'in the tape '12 at'this time.

Conductors 6, 1, 8, "9 and 10 are connected-by way cit-conductors I, 2, 3,1and 5 of cable 13 to the windings of the end-of-message reading relays -EM-l EM-2 EM- 3 and =EM--4 -respec tively. Energizationof conductors causes relay EM-el to operate by wayof conductor 1 of cable 13. Relay -EM-l locks through its -make contact and armature It to battery von conductor 15 supplied by the break'contacts of the sixth pulse-relay 1B of the'distrlbutorl. The'iopera- 2 tion of relay EM -l is without efiect-at this time, relay -EM-I releasing-upon the subsequent operation of the sixth pulse relay of -thesdistributor. Inasimilar manner, the signals corresponding to-the digits 5, 3, 2, 4, 3 and 1 arereceived and stored in the perforated tape 12 and also cause the operation of the end-.of-message relays EMI to EM-4 in code combination corresponding to each-of the digits stored in-the tape.

Immediately-following the signal for the digit '1 is the .end-of-messagesignal .which,in the assumed example, .is the signal representing the characterL having code .unitsl, 2 and 4 spacing and units 3 and imarking. This :signal causes relaysEM-2 and "EM- 4 to operate and lock .to battery on conductor 15, and relays EMI and EM- S to remain unoperated. Batteryat .armature I1 and make contact of relay EM--4 -is extended to armature xI Brand break contact of. relay EM3, armature leandmake contact of relay EM'2, armature -20 and break contact of relay EM-l and thence by way ofconductorfl .to'the 'winding or storage indicator .unit MR-4 and thence to ground. "The storage indicator may be of any'suitable'type, for.example asadisclosed in Haselton et a1. Patent "No. 2,155,825, .issued ltpr'il'25,l1939. 'Upon the release of relays JEM-2 and when thesixthpulsearelay1L6 operatesystorage indi'cator'unitIMR-.l is steppedor advanced one position .asits coil is again-.deenerglzed. Assuming no unposted messages for line 'L' preceded the transmission just described. indicator unit .MR-i will-now'be one position in advance of the setting on the storage indicator unit MP- i. contacts of units MR1 and 'M.P-l are connectedtogether,.so that whenever the two units since runit ilMR-i was advanced-one step .as the Like terminals of the bank posting equipment. .secondmessage.fromNew York over-lineL is also end-of-message character was recorded on the EM relays. Relay SI unoperated condition.

Returning-to line -L2, which it will be remembered is in the process of receiving amessage from an aircraft over Baltimore, let us assume that the aircraft operator completes his transis therefore now-in its 'mission slightly in advance of the transmission .of the end-.of-message signal over line L from New York, as noted above. Reception of the end-of-message character over line L2 has caused indicator unit MR2 to be advanced one position in a manner identical to that described above for unit MRI.

Disagreement between units MR-Z and MP-2 has caused the release ofrelay S2. As relay S2released, ground by way of its break contacts28 was applied to the armature and associated make springs 29'and 300i relays SI and S3 respectively, and thence over conductors I and 3, cable 3| to bank contacts P33and 36 of rotary switch SKR. Rotary switch .SKR. is stepped through a circuit from=ground on bank contact 33 of bank X, wiper arm 34, self-interrupting springs 35,-and coil of switch SKR tobattery. Bank position 32 however, is ungrounded at this time, and the self-stepping circuit of switch SKR is interrupted at this point. With switch SKR positioned so that its associated wipers are resting on the contacts 32, a circuit is established over bank Y to operate connect relay TC-I. The path may be traced from ground on wiper 31 of bank Y, through .bankcontact 32, thenceby way of conductor 2, .cab1e 33, through armature andbreak contacts 3-9 of unoperated relay S2, over conductor 2 of cable 4i! to the winding of relay TC-l, to bat- ..tery 4 l.

.ated. However, there has been recorded the reception of one comp-lete=message over line L which is awaiting connection to the common If it be assumed that the completed before the posting operation of the message received on line L2 is completed, unit MR-l will have been advanced an additional step by the reception of the second end-of-message signal, andnow will be two positions inadvance .of-associated unit MPI. Thus, it will be apparent, a count of unposted messages is continually maintained by the relative-positions of associated seeker indicator units.

.As the message-from line L2 is posted on the display board, unit NIP-2 is advanced one step over acircuit to be described later. Advancement of unit MP-2 again establishes agreement between settings .of .units MR-2 and -MP-2 and .relay S2 is reoperated over a circuit from battery I42 on Wiper 43 of unitMR-J, through bank contact 4'4 on MR2, bank contact45 of MP-2, Wiper 46 of MP-Z, conductor 2 ofcable 2-7, to the windingof relayS2, to ground. As relay S2 reoperates, the operate circuit from-relay TC-i isopened at breakcontacts 39 of relay S2. The

stepping circuit for rotary switch .SKR. is reestablished at this'time over a circuit from ground atbreakrconta'cts 29 of relay SI, make contacts .-28 of relaySZ, conductor QnOf cable 3!, bankcontact-=32 and wiper of switch SKR, through selfinterrupting contacts and coil of switch SKR 9 to battery. Switch SKR steps on self-interrupted pulses until it reaches an open circuit on bank contact 36. At this point, a circuit is established to operate relay TC which is similar to that described above for operation of relay TC-l.

Multiple range posting A detailed description of multiple range posting will now be given. Returning to the previous example of a message received over line L from New York containing a bound and control range posting for the Philadelphia fix section of the Washington flight progress board, there have previously been described the operations up to the point where connect relay TC, Fig. 1, has been operated under control of the seeker rotary switch SKR, indicator units MB;-l and MP-l, and associated relays.

Operation of distributor DR1.-Relay TC when operated, establishes a circuit to operate the clutch magnet SM! of distributor D-R l, Fig. 4. This path may be traced from battery 60!) on break contacts GM of relay RL3, Fig. 6, over conductor 4, cable li'lll, conductor lllll, Fig. 1, through make contacts ll of relay TC, over conductor l of cable llil, through break contacts 40l of relay ST, Fig. 4, to the winding of start magnet SMl, to ground. Energization of the coil of SMl attracts latch 402, thereby setting the distributor DR--l into operation. The en gagement of brush Bl of the distributor DEW-l with segment 2 of ring Bl closes a circuit from tongue I of the tape transmitter TTR-l. con-- tacts 48 of relay TC, conductor l of cable llll,

segment I of ring R2 of distributor DRr-l, brush Bl, segment 2 of ring Rl, conductor i of cable 403, break contacts 404 of relay DC, conductor l of cable 405, winding of relay lL-l to ground. The tongue I of tape transmitter TTRrl is in the closed position since the first digit of the flight identification number is 3, and therefore will apply battery M! to the circuit above described causing operation of relay lI--l. Relay lI-l locks over its make contacts 4%, conductor of cable 400, through break contacts 692 of relay RL3, Fig. 6, to battery 6513.

In a like manner, segment 2 of rings R5, R1 and R9 and associated brushes B2, B3, B l and B5 of distributor DR--l, Fig. l, closes circuits from tongues 2, 3, 4 and 5 of tape transmitter TTrl to relays lI2, lI--3, llI- l and iI5, respectively. However, none of these relays are operated since the first character perforation in the tape prevents all tongues of the tape transmitter T'I'R,l except tongue l from engagement with their associated contacts.

As the brushes of distributor DP,l are disengaged from segment 2 of rings El, R3, R5, R! and R9, the circuits from the tongues of tape transmitter TTR-l to the first digit identification storage and decoding relays lTl to lT---!l, are interrupted. When brush B5 engages segment 2 of ring Rll of the distributor DR-l, ground from break contacts 491 of relay DC over conductor 498 and segment 2 of ring R62 is applied by way of brush B t, segment 2 of ring Rl I, conductor 6 of cable llll, contact 55 of relay TC to the tape step magnet T53 of tape transmitter TTR--l to battery, thereby causing the tape magnet to operate and step the tape to the position where the second character in the message is over the tape pins.

As the brushes of the distributor DR-l move into engagement with segments 4 of rings RI, R5, R1 and R9, the tongues of tape transmitter TTR--I are connected through conductors 6, l,

8, 9 and it of cable 403, break contacts @519, Mil,

ll I, M2 and N3 of relay DC and conductors 6, l,

33, 9 and IQ, of cable 405 to the windings of the 5 second digit identification storage relays 2I--l to 2I-5, Fig. 4. This group of relays is identical with the first digit relays lIl to ill- 5 and is therefore indicated in diagrammatic form by the rectangles M4 and 421. The identification digit, 5. has the code unit 5 marking and units l, 2, 3 and i spacing and therefore relay 2I-5 will be the only relay of the second digit identification group to operate. The second digit identification storage relays look over the same circuit as described above for the first digit group.

As brush B5 of the distributor DR,i engages segment i of ring RI I, ground is again applied over the circuit previously described to the step magnet TS of tape transmitter TIr l, thereby advancing the tape l2 to the position Where the next character perforations corresponding to Fix 3 (Philadelphia) are over the feeler of the tape transmitter.

' As the respective brushes contact segment 6 of rings Bl, R3, R5, R1 and R9, battery is applied to conductor 5 l of cable 403, through break springs M5 of relay DC, through conductor ll of cable $05, to the winding of fix selection relay Fl, Fig. 5, to ground, causing operation of relay Fl which looks over its make contacts 500 and conductor 5%, conductor 5 of cable M6, to break contacts i H on relay RLl Fig. 4, to battery. With relay Fl operated, ground is extended through the pyramidal contacts of relays Fl to F5 to operate the Philadelphia fix relay, FX-3. The circuit may be traced from ground on make contacts 5% of relay Fl, through break contacts 503 of relay F2, break contacts 504 of relay F3, break contacts 5535 ofrelay F4,-break contacts 506 of relay F5, over conductor 3 of cable 501, to the winding of relay FX3, to battery. Relay FX-3 looks over a path through its make contacts 508, conductor 2 of cable 509, conductor 2 of cable ice, to break contactsBM of relay RL3, Fig. 6, to ground. As brush B6 contacts segment 6 of ring R, the tape transmitter receives another stepping pulse asprev'iously described and thev tape character over the feeler pins of tape transmitter TTR-l is now the range digit.

Engagement of segment 8 of the distributor rings by the brushes Bl to B5 applies battery over conductors l5, l1 and 2i! of cable 405 to operate range storage and decoding relays RI R2 and R5, Fig. 5, which lock over the same circuit as described for the fix selection relays. The operation of relays Rl, R2 and R5 closes a circuit through the pyramidal contacts of relays R-l to R5 to operate bound range transfer relay B. The circuit may be traced from ground on make contacts bit of relay Rll, through make contacts 5H of relay R2, break contacts 5l2 of relay R3, break contacts 5!? of relay R4, make contacts 5M of relay R5, over conductor 2 of cable 555 to the coil of relay B, to battery. The operation of range transfer relay B conditions the stepping circuit from distributor DR-l to the tape transmitter step magnet for reception of a single data digit and also transfers the pyramidal output of the first data translating relay group to the bound data storage relay group BS--l to BS-4, Fig. 6. Relay B operated closes a circuit from battery 539, through its make contacts 5lfi and conductor l8 of cable M1, to the winding of the B range restoration relay BR, to ground. Relay BR operates and looks over its make contacts 605 and con- .11 ductor 606 to break contacts 161.011 of relay AG, to battery.

As brush B6 contacts segment 8 of. ring RI I, the tape is again advanced and positioned so that the .data character 4 is over the tape transmitter feeler pins. When brush B6 contacts segment .9 of ring RH, azcircuit is established from ground on break contacts 418 of relay ST, through conductor 4I9, through :segment 4 of ring -RI:2 and brush B6 .to segment 9' of :ring RI I,.over conductor 420, to the winding. of relay DC, to battery, causing relay DC to operate and look through its make contacts 421 'to break contacts 423 of "relay ST, to ground.

Engagement of segment In .of :the distributor rings by the brushes BI to B5 applies battery over conductors 22 and 24 of cable 405 to operate data decoding relaysDT--2 and .DT-'4 which look over the same-circuit as described for the fix selection relays. The D]? and DU .relay groups are identical to section 424 of the II relay group and have thereforarfor simplicity, been. indicated in diagrammatic form as box 5|?! and box 5.5.6. Circuits through the :DT relay contacts may be traced by reference xto corresponding numbers on the pyramidal contacts of the [:1 relay group. Fhus, operation :of .-relays DT--2 and DT-4 establishes a circuit which-may be traced from battery SIB throughbreak contacts of relay DT-I (corresponding to 426 of "II-4), make contacts (428) of relay D'I.2', break contacts (429) of relay Dill- 3, make contacts (430) of relay DT-4, break contacts use of relay .DT-5, conductor 3 to make contacts 520 of range :connect 'relay B, conductor II of cable 5.I-1.,:to the winding of relay BS-3-,,,Fig.ifi, "to ground. Relay BS--3 locks over its make contactstlidrconductor 609' tobattery on break contacts 61M] .of relay .RL-3. The toregoing operation'whichresulted the energization of bound data storage relay ES 3 has, in effect, translated the character 4 from the 'teleprinter code to a pulsing code on the'pyramid'al contacts of relays DT-=I to .DT- .5, and has stored the resultant on storage relay BS-:3. .It will be understood that the: translation to pulsing code made on the contacts of the-,DT relays is ito-efi'ect subsequent pulsing, by .means of a number of stepping pulses, of the display indicator units to settings corresponding to the data digits transmitted from the remote teleprinter. to the operation of :relay,BS--3,. relayBR has also been operated and subsequently will be used to eitect the restoration to blank of any existing display on the selectedbound. data display indicator.

Following the above described operation, brush B5 of'distributor DR--:I.,.Fig. 4, contacts segment H) of ring RH and the-tape advanced one step. as described previously. Engagement of segment t2 of the distributorrings bythebrushes Bf to B5 applies battery over :conductor 26 of cable 405 to operate relay DU--I., Fig. 5, which looks over the same circuit as described for the DT relays. Operation of relay .DII- I has :no e'fiect at this time, since theicircuit from the pyramidal contacts is open at the V rel'aycontacts'. Distributor brush Bfilnext contacts segment 12 of ring RI? but no tape transmitter stepping action results since segment 5 of. ring R12 has hadiits ground connection removed -by the operation of range connect relay :3. Thecircuit may be'traced' from segment 5 of ring Hi2, overconductor '3 of cable M6, to "open break contacts "52I of operated relay B. As brush BS-contacts segment f4 ofring R1 a circuit is-estab'lished from ground on segment 6 :In addition of ring RIZ, through brush B5 :andsegment .I4 01 ring RI I, over conductor 433', to the winding of relay RL'I, to .battery. As relay RIP-I operates, the locking circuit to the fix, range, and data decoding relays is opened at break contacts 4-li'l of relay RLI and any of these. relays which have been operated are released. Release of the RI, R2 and R5 relayscauses release of relay Bwhich was being held operated through pyramidal contacts on these relays;

Since clutch SM--I is still energized, the brush arm of distributor 'DRI makes a second revoIution at this time. As brushes B1 to B6 contact segments 2, 4 and 6 of rings R1 to RM, :n-o-circuits are established since conductors I to I5 of cable 403 are opened at the break contacts-of 019- erated relay DC, and the ground connection to segment 2 of ring R12 of the tape-stepping ci-rcult is opened at break contact 401 of operated relay DC. As brushes Bl to B5 contact segment 8 of rings RI to R9, the R-I relay of the range decoding group is operated in accordance with the code for character 3 which is still over the tape transmitter feeler pins. Relay R-I locks over the circuit previously described and closes a circuit to operate range connect relay C, Fig. 5, over a circuit from ground on make contacts 511) of relay RI, through break contacts 522 of relay R2, break contacts 523 of relay R3, break con: tacts 524 of relay R4, break contacts 525 of relay R5, conductor 3 of cable M5, to the'WlIldi'Ilg of relay C, to battery. Relay C operated, transfers the output of. the DT relay decoding pyramid to the CS relay group in Fig. 6. Storage relay CS-l is operated as a result of the final data digit perforated in the tape in a manner similar to that described for the B data character. Relay C operated also causes operation of 'C data restorationrelay CR over a circuit-similar to that described for the operation of BR relay.

At this point, the data for the two ranges in the assumed transmission have been decoded and stored on the proper storage relay groups of Fig. 6 in readiness for the actual postin operation. Note that, if the data for the range in question consists of more than one digit, :as for example, V or over range, the tape transmitter stepping circuit is not opened as the brush B6 contacts segment I2 of ring RH, since the ground connection to segment 4 of ring RIT2 is uninterrupted by operation of V range connect relay.

Returning to the operations resulting from the example under consideration, as the brush arm of distributor DRP-I makes its third revolution, the final character in the tape is over the tape transmitter feeler pins, viz., the. Lor 'end-of-message signal. In the manner previously described, relays R3 and R-5 will :be operated as brushes B! to B5 of distributor DR contact segment 8 of the associated rings. Relays R-3 and R 5 operated, establish a circuit for operating the end-of-message relay EM, Fig. 2. The path may be traced from round on break contacts 525 of relay R'---I, through break contacts 521 of relay R-2, make contacts '528 ofrelay R--3,Jbreak contacts 529 of relay R-4, make contacts 530 of relay R-5, over conductor 3 of cable 509 to the winding of relay EM to battery. Relay EM locks over its make contacts 200 through conductor -2 of cable 400, to break contacts :604 on relay'RL--3, to ground.

Relay EM operated, establishes 'a circuit from battery on its make contacts ZllLoverconductor I of cable 6, to the winding of relay ST, Fig. 4, to ground. Relay ST operates and'locks over its make contacts 435 and conductor l-of cable llll through make contacts 41 of relay TC, o-ver conductor Hill, to conductor 4 of cable 450, to break contacts 60! of relay RL-3, Fig. 6, to battery.

The break combination of contacts 40! of relay ST opens the circuit to the winding ofstart magnet SM-l of distributor DR-l so that the latch. 402 will engage the brush arm and stop its movement at the completion of the third revolution. Break contacts 432 of relay ST open the locking circuit to relay DC which releases in readiness for the reception of the next incoming message. As relay EM operated, -a circuit was completed from battery on make contacts 202 of relay EM, over conductor l of cable 509 through make contacts 53l of operated relay FX3, to conductor 532, which is multiplied to number 3 contacts of a series of tap switches designated FSI to FS-I0. These tap switches are associated with corresponding rows of display information on the flight progress board and are manually settable to one of three positions corresponding to the three indicated fix displays. As indicated on Fig. 5, switches FS| and FS-Z, corresponding to indicator rows l and 2 of the display board, are turned to position l corresponding to Fix 1, or Washington. The tap switch for row 10 is turned to position 3 corresponding to Fix 3, or Philadelphia. As relay EM operated, another circuit was established from battery on make contacts 203 of relay EM, over conductor 2%, through break contacts 205 of relay VS, through break contacts 205 of relay AGR, over conductor 20"! to bank contact 268 of rotary switch RS. Bank contact 208 is the homing or idle position of the rotary switch, and therefore at this time, wiper arm 299 of rotary switch RS will be positioned to this contact. The battery connection to bank con-- tact 208 will, therefore, be extended by means of the wiper arm 259, through self-interrupting springs 2m and the winding of switch RS, to ground. Switch RS proceeds to step from its homing position under control of the selfl-interrupting contact springs. As wiper arm 209 contacts bank positions 2 to It, a batter connection is made over conductor 2, through break contacts 2l2 of relay AGR, break contacts 213 of relay VS, to battery 222. It is thus evident that, with relay EM operated, switch RS will step on self-interrupted pulses until either relay AGR or relay VS operates and opens the stepping circuit at break contacts 2I2 on relay AGR, or 2|3 on relay VS.

The flight locator circuits under consideration are designed so that a search is made for agreement of flight identification digits as between existing displays on the associated fix section and .the new identification information as stored on the pyramids 425 and 42! of the first and second group of storage and decoding relays, II and 21, Fig. 4. In order to effect this comparison, all flight identification digits displayed on the flight progress board are, duplicated on associated storage indicator units of suitable type, such as disclosed in the aforesaid Patent 2,155,825. These storage indicator units are shown on Fig. 5 as ITSI and IUSI to ITSI0 and IUS-l0, units ITSI and IUSl being associated with the tens and units digits of identification displayed on the number I row of the flight progress board. The search for agreement is initiated at the lowest numbered row assigned to the fix section in question and progresses upward until identification agreement is found or a row assigned to the fix section is reached in which the tens digit of identification storage is blank. If agreement is found, relay AGR, Fig. 2, is operated; if a vacant space is reached, relay VS is operated.

Returning to the present example, it will be noted on Fig. 7 that the two rows of the display board assigned to Fix 3, or Philadelphia, are in use and that flight 35 is posted in row number it. The manually settable tap switches for rows 3 and ID, or switches FS-9 and FS!0, will be positioned to contact 3, corresponding to the Fix 3, or Philadelphia, section of the display board. It will be recalled that we have previously traced a battery connection as far as number 3 contacts of the fix tap switches. Assuming that rotary switch RS has stepped to the number In bank contact position, a circuit can be traced from battery 229 to the number 3 contact of tap switch FSI5, through wiper arm 533 of FS-IO, over conductor I0, cable 534, bank 2l4, contact [0 of rotary switch RS, Fig. 2, wiper 2I5 of the switch,

wiper 2ft and contact ll] of bank 2|! on switch RS, conductorlll of cable 2l8, wiper arm 535 of storage indicator unit ITS-I0, bank contact 3 of unit ITSiil, conductor 3 cable 535, break contacts 435 of relay II5, break contacts 431 of relay |I4, break contacts 438 of relay II3, break contacts 439 of relay |I2, make contacts 445 of operated relay, lI--l, conductor 4 of cable M6, wiper 2l9 and contact ll] of bank 22!] of switch RS, over conductor H) of cable 22l to wiper 53"! and bank contact 5 of storage indicator unit IUS-lll, conductor 5 of cable 538 to the numerical pyramid 421 of the second digit identification storage and decoding relays 2| (which are storing the digit 5 and therefore have established a path from the apex of the pyramidal contacts to conductor 5 of cable 538 in a similar manner to that described above for conductor 3 of the IT group), to conductor 3 of cable 400, to the winding of relay AGR, to ground. It will be noted that the series circuit just described, which causes relay AGR to operate, is dependent on an exact agreement of both digits of identification as stored on indicators ITS-H1, IUSl 0 and the storage of the incoming message identification on relay groups II and 21. A search for this agreement was instituted on the first row of information under the Philadelphia fix section, as the rotary switch RS stepped over bank contacts 9, but since the identification displayed on row 9 did not agree with the identification digits transmitted in the incoming message, no complete circuit was established.

As noted before, operation of relay AGR, Fig. 2, interrupts the stepping circuit for rotary switch RS, which is therefore positioned at bank con- .tact number l0. Relay AGR operated, establishes a circuit from battery 222, through make contacts 223 of relayAGR, over conductor 224 to the wiper 225 and contact ID of bank 226 of switch RS, over conductor ID of cable 221 to the winding of gang relay =GA-l0, to ground. Relay GA--lfl is therefore operated and connects, by means of its make contacts, the pulsing multiple M9 to the display indicators in row Ill of the flight progress board, Fig. 2, and through cable 251 to the storage indicator units ITS-I0 and IUS-| 0 of Fig. 5. At this point, all preliminary storage and row selection operations have been completed, and the actual pulsing operation of the indicators in accordance with the transmitted information can be initiated.

amass -Opera'ti0n-o) distributor DR-Z Relay AGR opera'ted, establishes a circuit from battery 222 through make contacts '228 of relay AGR, over conductor "I of cable 229, through break contacts 6 of relay PR, Fig. 6, over conductor 4 of cable 229,to'the'winding of start magnet SM2 associated with distributor DR--2, to ground. Operation of start magnet SM-2 disengages the latch 6 I2 "from the brush arm, thereby setting distributor DEL-2 in operation. As brush BI of distributor DE -2 passes even numbered segments '2 to 20 of ring RI, ten pulses are transmitted to relay P1. The circuit may be traced from ground 613 on ring R2, through brush BI and segment 2 "of ring RI, conductor BI4 to the winding of relay P1, to battery. The ten pulses to relay P1 at this time serve 'to restore to the blank position any previous display which may appear on the indicators of the selected ranges, B and C, of the selected row. The

circuit may be traced from battery 6I5 through make contacts FIE of relay BR, conductor 2 of cable IiI'I, 'make contacts '6 I8 of relay PI, conductor 'I of cable 6I9, make contacts 230 of relay'GA-II'I, Fig.2, winding of display storage indi'cator BIO, break contacts (not shown) of display storage indicator BIO, (like the break contacts 23I of storage'indicator CIT-I in row one), 'to ground. The display-storageindicators shown in row ten are identical to the unit designated ITI, and therefore all except this unit are shown in diagrammatic-form. These units, which preferably are like the unit disclosed in Haselton et al. Patent 2,302,769, are unresponsive to restoration pulses when in the blank position due to the interruption of their pulsing circuits by the switching-contacts 23'] an'd232 which are disengaged from each other when "the indicators are at their blank settings. The indicator unit "in 13 range 'of row III of the display board will therefore utilize only such pulses of the ten in number originated by relay P'I'necessary to restore it to the blank position, at "which point 'the pulsing circuit is automatically opened. If the unit is already in the blank position, the restoration pulses are not effective. Indicator C10 in row 'III is cormected to restoration pulses over a circuit similar to that described for unit B10 under control of operated relay CR.

When the brush B l "contacts segment '22 of ring RI of distributor FDR-2, a circuit is closed from grounded ring R2 through brush BI and segment 22 of 'ring RI, over 'condu'ctor 820, to the winding of relay AG, to battery. Relay AG operates and locks over "a circuit through its make contacts 'B'2I and conductor 622 to break contacts 623' "of relay RL2, to ground. Relay -AG operated, opens the locking circuit for relays BR and CR at its break contacts 601. Relays BR and CR release and open the battery "circuits to contacts of the P1 relay which were used in the restoration pulsing operation previously described. RelayAG operated, at" its :make contacts 624 applies ground over con'ductor ID of cable 154'!) through contacts 234-o relay=G-A--IU to all contacts til-3 of the indicators in row ID of the display board. This latter circuit replaces the ground connection which is opened by contacts MI and 232 of. the indicator units when they are in the blank position and thus allows any units which may now receive pulses to step from the blank position. The manner in which indicator units BI'Il and 'CIO are actuated from their blank settings to display the digits 4mm 1 respectively will now be described.

As the distributor brush BI passes over the group of segments 24 to 42 of ring R'I, a single impulse may be generated from relay PI, two impulses from relay P2, four impulses from relay P4, and seven impulses from relay P I. If an indicator is to be set to display the digit the relay PI only is employed, if the digit 2 is to be displayed relay P2 only is employed, relays PI and P2 being employed to display the digit 3. The digit 4 is selected for "display on an indicator by the relay P4, the digit 5 "by the relays PI and P4, the digit-=6 by relays P2 and P4. When the digit 7 is to be displayed, relay PI alone is employed. The digit 8 is obtained from relays P1 and PT, the digit 9 from relays P2 and P1 and the digit 0 from relays P1, P2 and PT. The setting of the bound indicator BIO to display digit 4 will now be described.

It will be recalled that relay BS-3 was op'ermm to store the data for posting the bound range during the operations resulting from the decoding and storage of information as received from the incoming line under control of distributor DRI'. A battery connection from make contacts 625 on relay BS--3, over "conductor H of cable 626, is extended to contact '521 of relay "P4. When relay P4 ispulsingfour times as brush BI of distributor DR*2 passes segments 31, 3 35 and 31 of ring RI, this "battery connection ii extended to provide four pulses through contacts 621 of relay P4, over conductor 1 of cable 6|9, through contacts 230 of relay GA-I-IJ, to the winding of indicator Bl-0, to ground on relay AG, Fig. 10, over a circuit previously described, for the first impulse; and to ground through break contact 23I of indicator unit BIB for the remaining three pulses. Thus, indicator unit BIO will receive four stepping pul'sesand will be positioned thereby to display the digit 4. In a similar manner indicator unit CII] will be positioned under control of relays CS-I, Fig. 6, and PI to display the digit 1. At this point, the posting of the two ranges of data as received from the remote sending point has been accomplished simultaneously. Note that the identification "indicators in row II] were not reset, since the operation of relay AGR gave a positive indication that these units were displaying the same digits as was contained in the incoming message. Relay A'GR operated, at break'con'tacts 235, removes the battery connection to the apex of pyramids 424 and 414 on the II and 21 storage and decoding group of relays, thereby opening all pulsing circuits to the identification range of indicators.

As brush Bl' of distributor Dre- 2 contacts segment '43 of ring RI, a circuit is established from ground on ring R2, through brush B1 and segment '43 of ring RI, over conductor '628 to the winding of relay RIP-2, to battery. Relay RIP-'2 operates and at its breakcontacts 623 opens the locking circuit for relay'which'releases. As brush BI of distributor .DR2 contact'ssegmen't 4! of ring RI, 3, circuit isestablished from ground on ring R2, through brush BI and segment 41 of ring RI, over conductor 5 of cable 629, through break contacts 630 of relay PR, over conductor 63L to the winding of relay Rio-3, to battery. Relay RL3, in operating, opens the locking cirquit for the BS, CS, FX, II, 21 and EM relays, which now release. Relay EM, Fig. 2, in releasing opens the operate path for relay AGR which then releases. Release of relay AGR opens the operate path for relay G'A---'I0- which releases, opens the operate path for clutch magnet SM-2 of distributor DR"'2 causing the brush arm to .arzacss come torest .atthe end of -the revolution, and 4 closes the stepping circuit. for rotary switch RE:

which proceeds to step over self-interrupted pulses to-its homing position. .As .relay RL--3 operated, acircuit was closedfrom battery on break contacts=632 ofrelay W0, through make contacts .633 of relayRielover conductor 5 of cable 469, over conductor H32, through .make contacts 52 of-zrelay TC, over :conductorl of cable 53, to the winding of .seeker .stOrageindicatQr -=MP-l, toground. Upon ,therelease of relay RL3, storage indicatorMP-I is advanced one positiontorecord the posting of one-complete -message from line L, as previously described. .The

operation of relay RL- 3 alsoopens-the locking; circuit for relay STwhich is releasedas a result.

In the; assumed example, .there were two complete messages from line .L awaiting posting while the message from lineLZwas connected .to

the common posting eqizipment. .The ,posting of MRI and MP-.-l willnowbe but.one step out of agreement. Since theyarestillnot in agreement, howevenrelay S! will remain unoperated,

and asa result,--connect relay 'TOremainsin its operated condition. Therefore, as soon as-relay RL--.3 releases, the :start circuit for clutchmagnet SlVl--l of distributor-.DR-l will .be. energized as described before and vdecodingand .storageof the informationcontainedinthe second message "from .lineL will proceed .under .control of distributor DR-l.

:Blankrowlocator In order to explain the action of theiiight .locatorwhen the flight identification has not'been previouslyposted on the display board, let us.as sume thatthe identification numbers 22 for fix'l the message just described has accounted for oneof .these messagesandat the completion of this operation, the seeker storage indicator units or Washington, comprise .the first three char acters of the second message'from line L. The

operations up to the point where relay '0 a, is operatedwill not'be describedas they are similar to those outlined in detailforihe first message. Operation of relayEM closes thestepping circuit for rotary switchRS as previously described. Since fix l is involved inlthis message, bank contact I ofthe'FS tap switches will be .rnarkedwith-battery"from theElVI relay contacts. Referring to Fig. 7, it will be noted'that the tap switches for rows l to'5 .d'ftheboard are turned to position'l. As rotary sWitchiR'S- stepsto bank contacts associated with rowJ, a circuit will be .established'to search ifor agreement of identification as stored onthe'll andZIJreIay groups and the displayed iniormation'in TOW} as indicated on storage indicator units 'ITS-"l and IUS-E. Since agreementis.notestablished on .row i, rotary switch'RS continues its stepping action and next contacts :bank position The storage indicators 'ITS"2 andIUS-Z are-in the ""blank position indicating a vacant space in row E. of the display'board. 'A circuit isestablished [from contact l of tap swit'ch'FS-2 over conductor 2. cable F34, bankZ'M, contact 2 and wiper 2th of switch-RS, wiper 25B and 'bank"'2l1,.con-

tact-2, of switch'RS, conductor cable 2 ill, wiper 5439 of indicator 'ITS'2,-contact BL of indicator ITS-2, conductor 1, cable 54'! break contacts relay PR, conductor .2, cable .229. .to the-windingof relay V8,.toground. Thus, .the action of switcl-i BS is stopped by operation of relay VS. in a .rn-anner' sim-ilar to .that-described for relay AGR minithegprior example. Relay VS initiates circuit subsequently.

.action identical with that described previously -for relayAGR, with one .exception. Relay VS does not open the battery connection to pyramids -424 and- 414 .of the II and 21 relay groups. Therefore, on actuationpulsing. from distributor DR -2 .andrelays Pl,-l?2, P4 and Pl, the identification -display board, as wellas the identification storage indicatorsfor therow selected are pulsed to the setting corresponding to the stored, decoded. in-

-.formation :on pyramids Y424 and 4M of relay groups ll and 21. This is .necessary sincethe flight. number. had not been previously posted.

Automatic wipe-out .In order to explain the automatic wipe-out Ifeature, assume a message received from the aircraft over the'Baltimore fix contains a report'of "flight '22 over Baltimore at 33 minutes after the lhour. L2 would then be 22213311, wherein the firstztwo characters represent the identity, the :third the .fix,.the fourth the range (over, or V), the fifth The transmission of characters .overline ation and brush'Btis about to contact segment of ring JRI.

..As brush'Bl of distributor DR2 contacts segrment M of rin 'Rl, a circuit is established from ground on ring R2, through brush Bl andseg- =ment'44 of ring RI, over conductor 6 of cable629, through make contacts 4635 of operated relay VTSl,-over conductor "636 to the winding of wipe-out relay'WO, to battery. .Note that .any

of-the'vVTS relays-operated closes the path .for

operation of relay 'WO, so that whenever "an over range is, posted, relay'WO will beoperated In the example -noted, relay VTS--l will have been operated in order topost .thedigit 3 in the tens digitof over .range.

Re1ay vW10 operated, locks overits makev contacts .traced .from battery on make contacts "639 .iof

=53'1andconductor 1 of cable 629 to break con- .tacts638 of relay AG, to ground.

Relay W0 operated, closes paths to operate andfhold-all of therestoration relays, viz., 'TSZR, BR and CR. The-circuit for operating VR may be operated relay -WO, over conductor I ofcable ME to the winding of relay VR, to ground. Circu-its torelaysBR and CR are similar.

Asrbr-us'hLB'l of distributor DR2 contacts seglment' li ofring Rl a circuit is established'irom agroundlonringRLthrough brush Bl and segment 45 .of ring .Rl, over conductor 9 of cable 5619,

through rmake contacts 236 of operated .relay .GA.6 (which is embodied in theequipment .of row 5,Fig.f2), to the Winding of solenoid 80 6, toground. Solenoid SO--6 and the storage indi- -..cator .units in row 6 are identical with units indi- ;cated;for row .I, and like equipment reference numbers applyin bothwcases. The solenoids SO aredesigned sothat whenenergized, they rotate .cam shafts 231, which in turn bring four contact springs 138,139,140 and .24! .on the storage .indicatorunits'into electrical contact with'the contactsi lz, 2-43, '244 and 245 on the storage indicator units,.in accordance with the angular -setting of =thedisplay drums, thereby applying ground-246 to certainof thecontact springs, and inturmto-certain of the conductors l .to 24 -GEf cable v.241. .For .a -mor.e detailed description of the above operation, reference may be had to said Patent 2,302,769. It will be apparent that operation of solenoid S6 results in the connection of a plurality of outgoing conductors to ground in accordance with the permutation code on the contacts of the indicators in the selected row, such per-mutations being in direct relation to the characters displayed on the drums of the indicator units.

In the present instance, an over report has been posted on row 6 for flight 22 at Baltimore. The posting of an over range causes the automatic wipe-out of this flight posting at the previous fix along the airway. However, in order to determine the location of the previous fix, it is tion code on the storage contacts of indicator B6.

Tracing these grounded conductors in cable 241, it will be found that conductor I8 terminates at the winding of relay BT2, Fig. 3, and conductor 20 at the winding of relay BT4. The other terminal of the BT relay windings is connected to' battery and therefore relays BT-2 and BT-4 are operated. The right hand, or locking, windings of relays BT-2 and BT4 are not energized at this time. As relays BT-2 and BT-4 operate,

a circuit is established from ground On outer breakcontacts 366 of relay BT-I, through make contacts 3lll of relay BT-2, through break contacts 302 of relay BT--3, through make contacts 303 of relay BT4, over conductor 2 of cable 305 to the winding of direction relay S, Fig. 5, to battery. I

Relay S operates and looks through its make contacts 542 and conductor 6 of cable 54L to make contacts GM of relay W0, to ground.

As brush BI of distributor DR2 contacts segment 46 of ring RI, a circuit is established from ground on ring R2, over brush BI and segment 46 of ring RI, through conductor 2 of cable 629, through make contacts 543 of Baltimore fix relay FX--2, over conductor 544 to the left hand winding of auxiliary fix relay FX2A, to battery. Relay FX2--A operates and looks over right hand winding and make contacts 545 by way of conductor 6, cable 54I, to make contacts GM of relay W0, to ground. As brush BI of distributor DR-2 contacts segment 41, a circuit is established to operate release relay RL3 as described in detail hereinbefore, and the FX2, EM, AGR, GA6,

VT and VU relays are caused to release thereby.

While the original locking circuit for the II and 21 storage relay groups is opened by the operation of relay RL3, these relays do not release since the locking circuit has been supplemented by an additional locking path from relay W0 operated. This circuit may be traced from battery at make contact 642 of relay W0, over conductor 6 of cable 40!] to the locking contacts of the II and 21 relay groups. Thus, while fix, range and data storage relays for the over posting at Baltimore have been released, the identity storage relays have been held operated. In addition, a reference to the over posting is retained by the operated W0 relay, a reference to the Baltimore fix is retained by the operated FX2--A relay, and a reference to the bound direction is retained by the operated S relay. Note that the operation of RL3 relay at this time does not energize the stepping circuit to the seekerstorage indicator MP2 since the circuit is opened at break contacts 632 of relay W0. Thus the seeker is prevented from connecting another message to the common posting equipment at this time.

As brush BI of distributor DR-2 contacts segment 49 of ring RI, a circuit is established from ground on ring R2, through brush BI and segment 49 of ring RI, over conductor I of cable 629, through make contacts 546 of S relay, through make contacts 54! of operated relay FX2--A, to the winding of the FX-3, or Philadelphia, fix relay, to battery. Relay FX-3 operates and looks over its normal locking circuit which has been reestablished by the release of relay RL3 as brush BI left segment 41 of ring RI on distributor DR2. The operation of relay FX3 establishes the proper fix section for the wipe-out operation on a southbound flight reporting over Baltimore.

As brush BI of distributor DR--2 contacts segment 56 of ring RI, a circuit is established from ground on ring R2, through brush BI and segment 50 of ring RI, over conductor 3 of cable 629, through break contacts 643 of relay PR, through make contacts 644 of operated relay W0, over conductor 2 of cable 54I to conductor 3 of cable 509 to the winding of relay EM, Fig. 2, to battery. Relay EM operates and looks over a circuit previously described. Relay EM operated, starts the operation of the flight locator circuit in the usual manner and the gang relay GA9 for the ninth row containing identification number 22 (Fig. 7) in the Philadelphia fix section is operated. Operation of relay AGR in the flight locator circuit again closes the circuit of clutch magnet SM2, and distributor DR-2 is reoperated. As brush BI passes the even numbered segments 2 to 20, and relay P1 receives ten pulses, the indicators in row 9 of the Philadelphia fix section of the display board, as well as the storage indicators ITS-9 and ITU9, are restored to the blank position. It will be recalled that relays VR, BR and CR are held operated over circuits from make contacts on operated relay W0. The restoration pulsing circuits for the V, B and C range indicators are therefore under control of these relays in a manner previously described. Make contacts 645 and 646 of operated relay W0 supply restoration battery to pulse the identity display board indicators and the storage indicators ITS9 and IUS9 to the blank position.

As relay AG, Fig. 6, operates when brush BI reaches segment 22 of ring RI, the locking circuit for relay W0 is opened and relay W0 releases. The release of relay W0 opens the looking circuits for relays FX2--A and S, which now release. At this point, the circuits conditioned by the automatic wipe-out operation are normal and the remainder of the operations initiated by distributor DR2 are as previously described for an ordinary posting operation, it being understood that no actuation pulses to the indicators in row 9 are transmitted, since no data storage relays are operated at this time.

By use of similar circuits, an over report of a northbound flight posted on the fix 3, or Philadelphia, section of the flight progress board would initiate a wholly automatic Wipe-out operation of the flight posting at the previous fix 2, or Baltimore, section of the display board. In this instance, a circuit is established by the operation of the N, or north, direction relay, and auxiliary fix relay FX3A, to select the flight at the FX2 grounded conductor 2 of cable 250 to make contacts 3I2 of relay RPS-4, over conductor M3 to conductor 2 of cable 3i I, to winding of selector magnet 2 of reperforator RPF, to battery. The circuit over conductor 4 of cable 250 is similar.

As brush BI of distributor DR3 contacts segment 3 of ring RI, a circuit is established to operate relay RPP over a path from ground on ring R2 of distributor DR3, through brush BI and segment 3 of ring RI, over conductor 8 of cable 229, to the Winding of relay RPP, to battery. Relay RPP operated closes a circuit from ground on its make contacts 3 i5, over conductor M6, to the winding of punch magnet PM of reperforator RPF, to battery. As the punch magnet of reperforator RPF is energized, the code elements 2 and 4 for the character 4 are perforated in the tape 3II. Upon completion of the punching stroke, the selector magnets 2 and 4 of repertorator RPF are mechanically reset to their unoperated condition. As brush BI of distributor DR3 contacts segments 5 and 3 of ring RI, the second identification character is punched in tape 3i? under control of relays RPS2 and RPP.

The third character, representing the fix digit is perforated next under control of relays RPS3 and RPP which operate as brush BI contacts segments 3 and 3 of ring RI. The code elements for this character are selected from circuits originating at contacts of the operated fix relay, in this case relay FXI, Fig. 5. It will be recalled that the transmitted character for fix I was the teleprinter character I and therefore fix relay FXI conditions the operation, at this time, of selector magnets I, 2, 3 and 5 of reperforator RPF. The

circuits may be traced from make contacts 550,

551, 552 and 553 on relay FX-I, over conductors I, 2, 3 and l of cable 554, to make contacts 3I8, 3| 9, 320 and 32I of relay RPS-3, over conductors I, 2, 3 and 5 of cable 3H to selector magnets I, 2, 3 and 5 of reperforator RPF, to battery.

It will be noted on Fig. '7 that row I of the display board does not show data posting for the over, or V, range. As explained before, if no V translating relays are operated, relay VM, Fig. 3, remains unoperated. With relay VM unoperated, segment 2 of ring R2 on distributor DR3 remains ungrounded and therefore, as brush BI passes over segments I I to I8 of ring RI, no action results. Row I of the display board does contain data for B and C ranges, however, and therefore relays BM and CM will be operated. Relay BM operated grounds segment 3 of ring R2 on distributor DR3 over a circuit from ground on make contacts 322 of relay BM, over conductor 2 of cable 323 to segment 3, ring R2. A similar circuit from operated relay CM grounds segment 4 of ring R2.

As brush BI of distributor DR--3 contacts segment 23 of ring RI, a circuit is established to operate relay RPS'I over a path similar to that prevoiusly described for operation of relay RPS-I. Relay RPSI operated, by means of make contacts 324, 325 and 326, grounds conductors I, 2, and 5 of cable 3I I. Thus, the code elements I, 2 and 5, representing the B range digit 2, are selected for the next character perforation in the tape. As brush BI contacts segments 23 to 30, the B data, C range and C data characters are perforated in tape 3Il. Relay RPS-I I, operating from segment 32 of ring RI, is arranged to select the L, or end-of-message, character as the final perforation in tape 3II.

As brush BI of distributor DR3 contacts segment 34 of ring RI, a circuit is established from ground on ring R2, through brush-BI and segment 34 of ring RI, over conductor 6 of cable 229, through. make contacts 530 of relay PR, over conductor 63I to the winding of relay RL-3, to battery. Relay RL-3 now operates with results as described previously.

As brush BI of distributor DR3 contacts segment 25 of ring RI, a circuit is established over conductor II of cable 229 to make contacts 644 of relay W0, so that, if the message just received had contained an over report and relay W0 were operated thereby, the automatic wipe-out operation would be initiated at this time. With the example under consideration, relay W0 is not operated and therefore no action results from this circuit at this time.

As brush BI of distributor DR3 contacts segment 3% of ring RI, a circuit is established over conduct-or 3 of cable 229 to operate relay RL i. Relay RL-t opera-ted opens, at its break contacts 553, the locking circuit for relays PA and PR. Relays PA and PR thereupon release and in turn cause the release of the data translating relay groups BT and CT, as well as relays EM and CM. At this point all circuits have been returned to normal in readiness for reception of the next message.

From the foregoing description, it will be evident that a coded message has been perforated in tape 3I'I which comprises the exact context necessary to cause the tower display board to duplicate the current information displayed on row I of the main flight progress board. The coded intelligence characters in tape 3I'I are transmitted by means of tape transmitter 32'! and transmitter distributor 328 to line 329 which in turn terminates at the receiving distributor of the auxiliary, or tower, display board diagrammatically indicated in the figure.

Automatic retransmission of revised information Assume that an additional message is received which causes a posting in the over, or V, range of flight 43 on the Washington fix section of the main flight progress board. Since this flight has already been cleared to the tower as evidenced by the display of the digit 8 in the control range, it is apparent that the new information posted on the main board should also be retransmitted to the tower display board. Note that in this case, the retransmission should not be a duplication of all the information displayed on 'row I of the main board, but rather should be a retransmission only of the new or revised information posted by the latest message. A description of the circuit operations to accomplish this retransmission will now be given.

Since the posting operation under consideration does not contain data 3 for C range, the circuit to operate relay PA will not be established. However, as solenoid SOI is operated followinng the posting of the over range on row I of the Washington fix section, translating relays CT2 and CT-3 wil1 be operated under control of indicator C-I, which has been positioned to display the digit 8 by the previous posting operation, causing relay PR to operate as explained previously. Relay PR operated performs the same functions as described for the previous example. However, in the present case, since relay PA is unoperated, the ground connection from make contacts of relay PA to the windings of relays VM, EM and CM has not been established. A ground connection to the winding of relay VM has been established over conductor I 253; of: cable-55:1; by make-.contactsufifi! of relays connected irrparallel, to ground (Certain ot'the VUS relays will/be operated toestoreithe data: pulsing code for the-units digit .of.V range.) The VTT' and 'VUT. groupsrof translating. relays. will therefore look; over theirlockingi windings through relay VM, to: ground. The BT. and CT: groupsof: translating: relays wilil fail. to lock: since their. locking windingzcircuitsare opensat the; EM and CM relay coilv terminals.- The operation-otdis tributor DR,3 .will--- therefore causetape 3; toperforated to contain theeidentification -fin. V range, V data, and .end-of-message characters. only, segments .3 and: .4 f-=flng R2 on: distributor DR-SE being ungrounded dueto; relays Il3M .and-: CM remaining unoperated.

Automatic alarm circuits The system provides an indicator such as lamp 441:,1 Fig.- 4, which operates. whenever relaygroups. II and 21 are set to positions; representative of: code signals. other than the code, signals .ior 1 the digitsr-l .to 9 and, 0 such as may result fromethez tailure-ot line-L,. static: conditions, faulty operation of the teleprinter. keyboard. and thelike... Lamp 5551-01-1 Fig. aprovides a similarindication forzthe data-relay'decodinggroups.

Another" Warning. indication. is. provided.. by, lampefitiig Fig. 6, which. is operated whenever the VS and W0 relays sare operatedsimultaneously. The circuit may be traced: from batteryon make contacts; ZSS -ot relay-VS, over conductor 3. oifi cable- 229; through make contacts-.-664-; of relay over conductor 6 651-170 the windingofirelay, AR, to ground. Relay operates-and looks. over its make contacts. to battery on .break.- contacts 666;. of release key ARK. RelayARMoper ated closes a. circu-it'from battery onits make contacts 661,. tolamp 663, to ground, causing; lamp- 663 to light. The-operationiof1amp.663 is a- Warning -to.. the operating: zpersonneluthat an. over report has been received fromnancun scheduled aircraft-reporting. overla fix,. relay W0 operated-denoting. reception of an over. report and. relay VS. operated denoting. the. flight num. berhas not'been previously posted. The. over report. of an unscheduled.aircrattwouldlrequire immediate action on. the-panther the operating personnel in order .tofit the particular flight-into. the general trafficflom. LampdB-iprotides the alarm: feature to initiate such.'pr'oczecltuieiv E01- lowing' proper'oontrolaction, operation: of key ARK opens the.10cking ci1cl1i1i to: relay A-R which. is thereby" released, extinguishing, lamp 6634 M anual wipe-out Provision has. been. made for wipe-outotall infomnati-on in. any item-row of. thedisplay board by meansoi local teleprinter. operation- Such an operation would be necessary inthe eventa flight plan already displayed. on theuprogress. boardwere cancelled, or to. wipe-out the. display at the final. fix section of .a. control. centerwhere the automatic wipe-out featureiwould not-8421 3 To initiate such. a wipe-outoperation. the. local operatorat. teleprinter 3 would transmit. a.mes. sage containing the identification numberand fix section. number. of the flight. in question -in.-the same manner as hereinbefore described... How, ever, in place of therange character 1., 2}. 011,5; the wipe-out character. 7 would. nextsbe. transmitted,, followed. by the. standard end-. ot-.message character. As this-.messageis.connected by-the seeker in thecommon postingflequipment operas tical to-those'previously described up. to thepoint wherethei-ch-aracter '7 is stored-on the range decoding, relays R-l .to.R-- of Fig. 5. Operationyof relays Rl-, R-2 and R3,, corresponding to-code ,1, completes a ,circuit. through pyramidal contacts on relays R-l: tO Rr5itU operaterelay;.WO-;. The-circuit maybe traced. from ground. onmake springs 5510 relay Rt Fig. 5, through make springs 51 t relay";.P,2 the make: combinationofs z arings-ttit2v .ofvrelay R-3, breaksprings oicable-229,. over conductor Lof, cable 4-l6,,,to'

the windingof; relay ST,,Fig. 4; to ground. Relay ST -is. thereby operatedand opens at its break: contactsrd it, the groundqcircuit tosegments Wand and 510i ring RtZot distributor-DR-|'.1 There-- fore. as. brush so passessegments 4 and. 52- of ring .Ri'Z,- no stepping circuit is completed to thetape. transmitter. On. theenext. revolutionv ofd-istrihutor BR- the ended-message character issstored and decoded .as. herein-beforedescribed and the flight locator and2 pulsing; distributor DR.2. action-.fol-1ows.-

The indicators in; the sea lected. row of the displayboard are thusrestored toblank under-control ofi operated relay'WO'.

Variousmodifications otthe circuit arrange.-

ments and apparatus shown, and the various.

' equivalents orsubstitutes for -the devices illustrated, will readily occur. to those'versed' in the art-:-with'out...departingfromth'e spirit and scope of the present: invention. Thed-i-sclosure, there-- fore;v is for the purpose 0t illustrating the prinr cipl-es ot the inventionwhich isnot to .bere garded as limited except as: indicated by the scope oicthe. appended claims;-

What is claimed is:

1. In an airway; schedule posting. system, a fiightprogress board. divided into; panels one for each fixwan-dreacha panel-comprisingga plurality of. rows of... changeable. indicators.- fordisplaying flight data including overtimes. meansofor. post-1 imgtheovertime of. a :fl-ight at a .fi-X in the cor respondingv fixpan-el inthe. particular spacedise playing data forthatflight; as,--previously posted, and means acting; automatically upon the posting of. an. overtime fora-flighttat a-particulanfix panel to cause the. data for thatrfiightatjthepreceding fix panel to be. wipedeout. by. the restoration. to blankspositions: of. the, indicators displaying such data.

2- A: system. tor posting-information:regard ing. a plurality .of items. comprising. an announcing, board having. a. plurality of electro-responsiv eposti-ng devices assignable at v different times to difierent ones of saidritems ,andarranged different. displaygroups respectively classified in regardto. difierent. particulars. vofan item, ,each posting. device including. a; pluralityof display means.respectively-actuatable to. difierent settings for displaying ,-a. plurality .ot data..concerning one ofsaid items, a. sourceof message posting signal-s comprising. item and. display group designation and detain. regard. tot anlitem means responsive to said: item and. .displaygroup designation: signals for... selecting. at particular. disp lay g-roupi'andn a posting. device within .said rgfroupwassigned tor the tionsundercontrotot.distributoriDRp-l.are-idenitem representedi byzthe item designation. signals, 

